[llvm] [AArch64] Implement vector splitting for histogram intrinsic (PR #103037)

[Sander de Smalen via llvm-commits]

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@@ -25434,6 +25436,41 @@ performScalarToVectorCombine(SDNode *N, TargetLowering::DAGCombinerInfo &DCI,
   return NVCAST;
 }
 
+static SDValue performHistogramCombine(SDNode *N,
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sdesmalen-arm wrote:

Rather than doing this as a target-specific DAG combine, this should be done as generic type legalisation in LegalizeVectorTypes.cpp. See `DAGTypeLegalizer::SplitVectorOperand` for how this is done for other operations.

https://github.com/llvm/llvm-project/pull/103037